Techniques based on the method of modal expansions, the Rayleigh-Stevenson expansion in inverse powers of the wavelength, and also the method of moments solution of integral equations are essentially restricted to the analysis of electromagnetic radiating structures which are small in terms of the wavelength. It therefore becomes necessary to employ approximations based on "high-frequency techniques" for performing an efficient analysis of electromagnetic radiating systems that are large in terms of the wavelength. One of the most versatile and useful high-frequency techniques is the geometrical theory of diffraction (GTD), which was developed around 1951 by J. B. Keller [1,2,3]. A class of diffracted rays are introduced systematically in the GTD via a generalization of the concepts of classical geometrical optics (GO). According to the GTD these diffracted rays exist in addition to the usual incident, reflected, and transmitted rays of GO. The diffracted rays in the GTD originate from certain "localized" regions on the surface of a radiating structure, such as at discontinuities in the geometrical and electrical properties of a surface, and at points of grazing incidence on a smooth convex surface as illustrated in Fig. 1. In particular, the diffracted rays can enter into the GO shadow as well as the lit regions. Consequently, the diffracted rays entirely account for the fields in the shadow region where the GO rays cannot exist.

Product Description: An essential sourcebook for students and the only reader to cover such an extensive time period, this unprecedented collection of primary texts is organized in three parts, mirroring the three Art & Visual Culture textbooks. Included are extracts from Vasari, Panofsky, Ruskin, and more, on topics from sacred art to landscape design and the birth of modernity...read more

Product Description: This new, thoroughly updated edition of a popular formulary includes current drugs. The practical format is exceptionally concise, portable, and easy to use, and offers readers immediate access to essential information on therapies for dogs, cats, horses, ruminant species, pigs, birds, rodents, rabbits, ferrets, and reptiles...read more

Product Description: Art of the Avant-Gardes is the second of four books that make up the Open University's Art of the Twentieth Century series. It discusses the development of modern art in the first third of the century. The book opens with an essay that introduces the main themes of art in the period and summarises the political context in which it developed: the First World War, the Russian Revolution and the subsequent consolidation of the European dictatorships...read more

Product Description: This book, the third in the Art of the Twentieth Century series, considers works of art produced in Europe and the United States between the 1930s and the 1960s.Arranged in four main parts, this abundantly illustrated book begins by examining aspects of the European avant-garde from the 1930s to the aftermath of the Second World War...read more

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Product Description: Art in Theory (1648-1815) provides a wide-ranging and comprehensive collection of documents on the theory of art from the founding of the French Academy until the end of the Napoleonic Wars. Like its highly successful companion volumes, Art in Theory (1815-1900) and Art in Theory (1900-1990), its' primary aim is to provide students and teachers with the documentary material for informed and up-to-date study...read more (view table of contents, read Amazon.com's description)

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Product Description: This volume traces the challenge posed to the academic canon by the emergent avant-garde of the early and mid-19th century. It considers the shifts in its development through the later 19th and 20th century and its eventual incorporation as a form of modern canon by the eve of World War II...read more